Combating weeds with lower alkyl 3-phenylcarbamoyloxythiolcarbanilates

ABSTRACT

WEEDS ARE COMBATED IN BOTH SOYBEANS AND SMALL GRAINS BY POST-EMERGENT APPLICATION OF LOWER ALKYL 3-PHENYLCARBAMOYLOXYTHIOLCARBANILATES, FOR EXAMPLE, S-ETHYL 3(N&#39;&#39;-M-TOLYLCARBAMOYLOXY)THIOLCARBANILEATE.

United States Patent s 701 646 COMBATING WEEDS wiTH LOWER ALKYL 3- PI-IENYLCARBAMOYLOXYTHIOLCARBANILATES Ralph P. Neighbors, Olathe, Kans., assignor to Gulf 3,701,646 Patented Oct. 31, 1972 commercial methods. Lower alkyl chlorothiolformates, m-aminophenol and the phenyl isocyanates are all articles of commerce. The procedure for manufacture of one of the novel herbicides is presented below by way of illustration.

Research & Development Company, Pittsburgh, Pa. 5 No Drawing. Filed Aug. 13, 1969, Ser. No. 849,857 PREPARATION OF ETHYL 3-(3,4-DICHLORO- Us Cl 71 100 Int. Cl. A01n 9/12 1 cl PHENY-L) CARBAMOLYOXYTHIOCARBANILATE mm Ethyl N-(S-hydroxyphenyl)thiolcarbamate (7.9 g., 10 0.04 mole), benzene (100 ml.) and a trace of catalyst ABSTRACT OF THE DISCLOSURE (triethylenediamine) was treated dropwise With a solution of 3,4-dichlorophenyl isocyanate (7.5 g., 0.04 mole) Weeds are combated lioth soybeans and small grams in benzene (50 ml.). The mixture was heated to reflux by posbemergeilt apphcrfltlon of lower alkyl 3-pheny1' temperature, the heat source removed, and stirring concarbamoyloxythiolcarbamlates, for example, S-ethyl 3- finned for two hours The Product was removed by (N 'm'tolylcarbamoyloxy)thlolcarbamlate' filtration, washed with hexane (50 ml.) and dried. There was obtained 13.6 g. (M.P. 146148 C.; 88%) of DESCRIPTION OF INVENTION zglglambitgii (3 ,4 dichlorophenyl)carbamoyloxy] thlol It has recently been discovered that certain alkyl 3- 2O Analysis.--Calculated for CHClNOS (percent): C, phenylcarbamoyloxycarbanilates have the rather rare 49.89; H, 3.66; N, 7.27. Found (percent): C, 49.92; H, property of relatively high phytotoxicity toward a number 3.71; N, 7.02. of plant species but relatively low toxicity toward sugar Below are listed herbicidal compounds made by the beets. I have now discovered that certain lower alkyl procedure illustrated above:

Compound Analysis (calcdJl'ound) No, Name M.P. C.) Carbon Hydrogen Nitrogen 1 Ethyl 3-(3,4-dichlorophenylcarbamoyl- 146l48 49.s9/49.92 3. 66/3. 71 7. 21/7. 02

oxy)thioloarbanilate. 2 Ethyl 3-(phenylcarbamoyloxy) thlolcar- 138-140 60.74/60.47 BAG/4.83 8.85/8.80 3 Eiii???fet shlorophenylcarbamoyloxy) 156-168 64.78/54.70 4.31/4.20 7.98/7.96

thiolcarbanilate. 4 Ethyl3 (m-tolylcarbamoyloxy)thiolcar- 151-153 61.80/6L71 5.49/5.4l5 8.47/8.08

bam'late.

3-phenylcarbamoyloxythiolcarbanilates have high phyto- USE OF THE HERBICIDE tfmmty towarq .Sugar beets and many W but rela' So as to illustrate clearly the selective phytotoxic uvely 10W f i Soybean? whlch also properties of the herbicides, a group of controlled greenusual, there being very little selection of weed control house experiments is described below. agents available for either sugar beets or soybeans. 40

Briefly, the novel class of herbicides of this invention gost-emel'gem 1 36 may be represented by the structural formula All aqueous dlsliefslon of each actlve compound W 0 H prepared by combining 0.4 gram of the compound with g about 4 ml. of a solvent-emulsifier mixture (3 parts of O a commercial polyoxyethylated vegetable oil emulsifier, H one part xylene, one part kerosene) and then adding Rsc-N-H water, with stirring, to a final volume of 40 ml. in which R is a lower alkyl group having from one to The species of plants on which each compound was four carbon atoms and X and Y are selected from the to be tested were planted in four-inch pots in a greengroup consisting of hydrogen, chloro, methyl, ethyl, house. Ten to eighteen days after emergence of the plants, propyl, isopropyl, butyl and tert.-butyl. These compounds three pots of each species were sprayed with an aqueous maybe synthesized and formulated into agricultural spray dispersion of the active compound prepared as described mixtures by conventional methods. Post-emergent apabove, at a rate of 5 lb. of active compound per acre plication is preferred, the compounds being effective at and at a spray volume of 60 gallons per acre. Approxiapplication rates of from about 1 lb. per acre to 5 lb. mately one Week after the p y ppli ation the plants per acre where l t are t t t d f th spray, were observed and the results rated according to the to]- In heavy infestations where some weeds are sheltered l wing Schedule: by others, either a higher rate of application or a re- Type of action: Degree peated appl1cat1on may be necessary, as will be under- C=chlorosis (bleaching) 0:110 efiect Stood those Sklned 1n the N=nec osis ff t SYNTHESIS OF THE HERBICIDES G=gmwth inhibition effect.

F=formative effect (a b n o r m al The herbicides of this invention are conveniently made form of growth) 3=severe effect. by reaction of an N-(3-hydroxyphenyl)thiolcarbamate K=non-emergence 4=maximum elfect with a phenyl isocyanate. These intermediates are readily (all plants died). made by known methods. The thiolcarbamate intermediate may be made by reaction of an alkyl chlorothiol- Th6 same i ifq g g if to Judge formate with m aminophenol by a method of the type grsvergent resu s 0 arm accor ing tot e procedure beexem lified by the proce we of Riemschneider and Lorenz: Monatsch. Chem vol. 84, p. 518 (1953). The (2) Pre'emergent use phenyl isocyanate is made by reaction of the correspond: ing aniline with phosgene by any of the well known A solution of each active compound was prepared by dissolving 290 mg. of the compound to be tested in 200 ml. of acetone. Disposable paper trays about 2 /2 inches deep of molded pulp were prepared and seeded with a variety of species of plant seeds, then sprayed with the acetonesolution at the rate of 10 1b. of active chemical per acre of sprayed area. One tray, which had been seeded I claim:

1. Combating weeds in the presence of a growing crop of soybeans by applying post-emergently to the locus of the weeds an effective amount of a 3-phenylcarbarnoyloxythiolcarbanilate of the structural formula 5 with alfalfa, brome, flax, oats, radishes and sugar beets 0 H was held at 75 F. day temperature; another seeded with U corn, coxcomb, cotton, crabgrass, millet and soybeans 0 H O CN Y was held at 85 F. Twenty-one days after seeding and H treatment the plants were examined and herbicidal efiect 10 R s N X was rated according to the above schedule.

Both post-emergent and pre-emergent results are set forth in the following table.

RESULTS OF POST- AND PRE-EMERGENT USE AS HERBICIDES Com- Grain pound Crab- Cox- Mil- Soy- Cot- Sugar No. Use grass comb Brome let bean ten 7 Alfalfa Oats Corn Flax Radish beet Wheat; ghum Tomato N1 N2 N1 N3 N3 N2 G1 G1 N4 G1 N1 G3 G3 N4 G2 N1 N3 N1 N3 G1 N4 N4 G2 G1 N4 N4 N4 G2 G1 N4 RESULTS OF POST- AND PRE-EMERGENT USE AS HERBICIDESContinued Com- Grain pound Crab- Cox- Mil- Soy- Oot- Sugar 0. Use grass comb Brome let bean ton Alfalfa Oats Corn Flax Radish beet Wheat N3 N2 N1 N1 3 N4 N1 G3 N4 G2 G1 N4 N4 N4 G1 Pie... 0 0 0 0 0 0 0 0 o 0 0 N1 N3 N2 N3 N4 G1 N4 N4 G3 G1 N4 N4 N4 G2 G1 N4 Pre 0 G1 0 0 0 0 0 0 0 0 0 0 It will be observed from the results tabulated above that 35 in which R is a lower alkyl group having from one to pre-emergent phytotoxicity of these compounds is practically negligible. A second series of tests of post-emergent activity at much lower rates of application was conducted according to the above procedure and results were rated four carbon atoms and X and Y are selected from the group consisting of hydrogen, chloro, methyl, ethyl, propyl, isopropyl, butyl and terL-butyl.

in the same manner. These results are tabulated below. 40

1; So Sugar Grain iiiiiiiiili l b J i Millet bear is Cotton Alfalfa Oats Corn Flax Radish beets Wheat sorghum Tomato 1 2 N3G3 N1 N2G1 NsGs 0 0 mm N3G2 N3G3 N2G2 0 2 1 N3G3 N1 0 N1 0 0 N1G1 N2G2 N3G3 N1G1 0 c2 2 2 N4 N1 'N4 N4 N2G1 N1G1 N4 N3G3 N4 N2G2 G1 N4 1 N3G3 N1 N4 N4 N1 N1 N3G3 N2G1 N4 N1G1 0 N4 3 2 N3G3 N1 N4 N3G3 N1 N1G1 N4 N3G3 N4 N1G1 o c3N3G3 1 N3G2 0 N2G2 N3G3 N1 N1 N4 N2G1 N4 N1G1 0 C2N2G2 4 2 N4 N1 N4 N4 N2G1 N1G1 N4 N4 N4 N302 0 N4 1 N4 N1 N4 N4 N1G1 0 N4 N8G3 N4 N2G2 0 N4 References Cited UNITED STATES PATENTS 3,404,975 10/1968 Wilson et a1. 71-100 JAMES O. THOMAS, 114., Primary Examiner US. Cl. X.R. 260-455 

